Advertisements on the Internet include various kinds of forms such as a banner advertisement, a mail advertisement, a keyword targeted advertisement, and an affiliate advertisement, and in order to enhance the effect of the advertisement, the advertisement may be displayed at a position which can be easily noticed by users, or the advertisement may be blinked, or incentive is given to encourage users to access the advertisement. For example, Patent Document 1 discloses a prize service method for performing prize processing in accordance with the state of access by a user to a web site, wherein when the user accesses one of multiple web sites, winning determination is output with a predetermined winning chance, and when the winning determination is output, a banner advertisement included in the web page accessed by the user is changed to a winning banner including a display of the winning determination.